for a tank of that size, your best bet is to probably go for small to medium sized cichlids. They are fun to watch specially when caring for their brood and they have tons of attitude.
I would suggest any of the following:
1 Jack dempsey
1 female Green Terror if your getting a 60G
Pair of Archocentrus Centrarchus (flier cichlid) (and maybe a few dithers? not sure)
Pair of convict cichlid and a few dithers
Pair of Cryptoheros Sajica and a few dithers
Other medium sized cichlids such as Spiny Cichlid, Blue Acara, Honduran Red Point, Amatitlania Kanna etc, etc